oracle中的内存块SGA和后台进程详解（sqlplus）

oracle有一个很大的内存块，称之为 系统全局区(SGA)，在这里它会做以下工作：

维护所有进程需要访问的多种内部数据结构

缓存磁盘上的数据，另外重做数据写至磁盘之前 先在这里缓存

保存已解析的sql计划

等等

oralce有一组“附加到”SAGde 的进程，附加机制因操作系统而已。

windows中，这些进程只是使用了 C调用(malloc)来分配内存，因为它们实际上是一个大进程中的线程，所以会共享相同的虚拟内存空间。oralce还有一组供数据库进程/线程读写的文件(只允许oralce进程读写这些文件)。这些文件保存了所有的表数据、索引、临时空间、重做日志等

oracle后台进程是构成实例的持久性进程，从启动实例开始，这些进程会一直运行，直至实例关闭。

有一点需要注意，这些都是进程，而不是单个的程序。二进制可执行文件只有一个，就是oracle。

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官网(下载PSTools,解压缩PSTools.zip，运行pslist.exe，窗口一闪而过

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解决方法：将pslist.exe文件拷贝到C:\Windows\System32目录下

验证：进入命令行，输入pslist:

C:\Users\Administrator>pslist

PsList v1.4 - Process information lister
Copyright (C) 2000-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

Process information for 20180314-120628:

Name                Pid Pri Thd  Hnd   Priv        CPU Time    Elapsed Time
Idle                  0   0   4    0      0    24:50:24.047     6:26:57.402
System                4   8 139  705    124     0:03:20.757     6:26:57.402
smss                296  11   3   32    700     0:00:00.093     6:26:57.324
csrss               508  13   9  723   2716     0:00:02.558     6:26:51.910
wininit             636  13   3   86   1964     0:00:00.140     6:26:50.616
csrss               656  13  13  999   4052     0:00:18.220     6:26:50.600
services            692   9   5  245   6024     0:00:01.622     6:26:50.506
lsass               716   9   8  787   5676     0:00:05.226     6:26:50.460
lsm                 724   8  10  155   2640     0:00:00.046     6:26:50.460
svchost             820   8  11  391   4896     0:00:03.946     6:26:49.914
nvvsvc              880   8   4  122   3112     0:00:00.109     6:26:49.789
svchost             920   8  11  371   5144     0:00:00.811     6:26:49.773
svchost             984   8  23  575  24888     0:00:04.243     6:26:49.742
svchost            1016   8  20  474 125612     0:01:11.744     6:26:49.711
svchost             336   8  24  708  14216     0:00:01.107     6:26:49.695
svchost             516   8  34 1268  23428     0:00:03.541     6:26:49.680
winlogon            768  13   3  114   3452     0:00:00.265     6:26:49.383
igfxCUIService     1136   8   6  122   2608     0:00:00.062     6:26:48.244
svchost            1204   8  17  495  15148     0:00:05.366     6:26:48.198
nvxdsync           1388   8  13  292  12812     0:00:04.118     6:26:47.137
spoolsv            1644   8  19  396  24084     0:00:00.265     6:26:46.022
svchost            1676   8  18  325  15308     0:00:01.528     6:26:46.002
armsvc             1804   8   4   77   1264     0:00:00.015     6:26:45.742
svchost            1828   8  10  148   3672     0:00:00.046     6:26:45.282
IMEDICTUPDATE      1892   8   4   62   1632     0:00:00.000     6:26:44.882
oracle             2044   8  31  652 1128724     0:00:26.629     6:26:42.942
OSPPSVC            1128   8   3  155   6260     0:00:05.148     6:26:41.732
QQProtect          1752   8  20  370  15900     0:00:01.092     6:26:33.132
Service_KMS        1760   8   8  482  25864     0:00:00.967     6:26:31.682
TeamViewer_Service  2008   8  19  364   5156     0:00:00.577     6:26:30.636
WmiPrvSE           2408   8   6  214   6900     0:00:00.405     6:26:06.503
dwm                2688  13   5  156  35240     0:01:18.889     6:26:02.650
explorer           2744   8  36 1203  56432     0:00:28.470     6:26:02.619
taskhost           2780   8  13  291  30576     0:00:03.712     6:26:02.588
PresentationFontCache  2936   8   6  156  26684     0:00:00.156     6:26:01.433
rundll32           2968   8   3   79   2212     0:00:00.015     6:26:01.355
RAVCpl64           1484   8  11  266   9184     0:00:00.156     6:26:00.934
RAVBg64            2324   8  10  209  15096     0:00:00.078     6:26:00.903
RAVBg64            2576   8  10  204  15100     0:00:00.109     6:26:00.887
YunDetectService   3128   8  15  198   5640     0:00:00.109     6:26:00.435
TSVNCache          3468   8  25  112   4204     0:00:00.202     6:25:57.985
jusched            3740   8   2   87   2332     0:00:00.015     6:25:54.556
WmiPrvSE           3800   8   6  128   3616     0:00:00.078     6:25:53.889
svchost            3952   8   6   97   1924     0:00:00.046     6:25:53.530
svchost            4000   8   5  102   2568     0:00:00.078     6:25:53.515
SearchIndexer      1300   8  14  894  50588     0:00:20.030     6:25:52.142
igfxEM             3200   8   5  129   4588     0:00:00.124     6:25:51.814
wmpnetwk           3516   8   9  282   8532     0:00:05.428     6:25:51.752
igfxHK             3908   8   7  288  11644     0:00:00.249     6:25:51.533
igfxTray           3764   8   4  114   3888     0:00:00.062     6:25:51.533
svchost            4128   8  19  342   7292     0:00:16.239     6:25:50.363
bee                5060   8  71 1375 106664     0:00:31.449     6:24:15.078
bee.worker         5112   8  10  274  63416     0:00:49.935     6:23:48.364
bee.worker         2372   8  10  180  33672     0:00:01.014     6:23:46.674
OUTLOOK            2716   8  43 4505 128100     0:00:32.370     6:23:06.948
idea64             1600   8  39  761 1016380     0:07:52.277     6:22:34.805
fsnotifier64       4100   8   4   28   3828     0:00:04.305     6:21:59.924
conhost            3704   8   1   36   1716     0:00:00.015     6:21:59.924
chrome              996   8  44 1514  76576     0:02:16.110     6:21:05.199
chrome             1332   8   7  109   2808     0:00:00.015     6:21:04.963
chrome             3044   8   2   66   3200     0:00:00.046     6:21:04.074
chrome             1376   8  20  303  96184     0:02:50.446     6:21:03.154
SogouCloud         3732   8  22  288  11588     0:00:35.693     6:14:57.895
taskhost           5760   8   6  231   7432     0:00:00.140     6:11:40.326
rundll32           1692   8   2  119   3352     0:00:00.062     6:03:15.150
chrome             6732   4  18  386 189812     0:03:41.521     5:43:45.876
AcroRd32           3604   8  11  276   9212     0:00:01.934     5:41:29.087
AcroRd32           6320   8  18  445 148364     0:00:15.241     5:41:28.116
cmd                4624   8   1   25   2312     0:00:00.015     5:38:22.396
conhost            5116   8   2   64   2260     0:00:01.482     5:38:22.336
java               6808   8  13  317  79604     0:00:02.542     4:37:03.609
conhost            6724   8   1   37   1716     0:00:00.015     4:37:03.600
navicat            5524   8   3  201  15616     0:00:11.481     2:17:32.728
uedit64            5956   8  11  210  48388     0:00:03.868     0:10:41.103
chrome             2840   4  16  232  43636     0:00:03.525     0:10:10.922
chrome             7136   4  18  250  60104     0:00:08.470     0:09:56.386
chrome             6604   4  16  245  46376     0:00:02.605     0:09:04.193
chrome             3280   8  24  381  82884     0:00:24.507     0:08:01.450
audiodg            3476   8   6  146  17164     0:00:00.514     0:04:09.356
SGTool             6680   8  15  392  10972     0:00:02.667     0:03:30.078
SGPicFaceTool      2672   8  21  295   5320     0:00:00.062     0:01:31.659
pslist             5000  13   1  164   2576     0:00:00.093     0:00:00.125

pslist name显示指定名称的进程信息例如：pslist oracle

C:\Users\Administrator>pslist oracle

PsList v1.4 - Process information lister
Copyright (C) 2000-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

Process information for 20180314-120628:

Name                Pid Pri Thd  Hnd   Priv        CPU Time    Elapsed Time
oracle             2044   8  31  654 1128740     0:00:29.343     7:05:24.242

这个oracle进程有19个线程(以上所示的Thd列)，还可以用pslist查看各线程的更多详细信息：

C:\Users\Administrator>pslist -d oracle

PsList v1.4 - Process information lister
Copyright (C) 2000-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

Thread detail for 20180314-120628:


oracle 2044:
 Tid Pri    Cswtch            State     User Time   Kernel Time   Elapsed Time
 352   9       170     Wait:UserReq  0:00:00.031   0:00:00.093    7:49:47.636
1060   8         8     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:47.136
1104   9       287     Wait:UserReq  0:00:00.187   0:00:00.062    7:49:47.126
1228  10        11     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:45.501
1480   8     26595     Wait:UserReq  0:00:00.031   0:00:00.000    7:49:39.277
1448  15   2119637   Wait:DelayExec  0:00:00.000   0:00:00.015    7:49:39.261
1468   8     23621     Wait:UserReq  0:00:00.015   0:00:00.000    7:49:39.246
1476   8     38570     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:39.230
1472   8     19605     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:39.230
1444   8     22768     Wait:UserReq  0:00:00.015   0:00:00.031    7:49:39.230
1464   8     66808     Wait:UserReq  0:00:00.624   0:00:00.015    7:49:39.215
1456   8     24398     Wait:UserReq  0:00:00.031   0:00:00.015    7:49:39.215
1548   8     33397     Wait:UserReq  0:00:00.156   0:00:00.093    7:49:39.215
1588   8     33704     Wait:UserReq  0:00:00.234   0:00:00.156    7:49:39.199
1596   9     85007     Wait:UserReq  0:00:00.577   0:00:00.546    7:49:39.199
1592   8     19276     Wait:UserReq  0:00:00.530   0:00:00.124    7:49:39.199
1608   8     12189     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:39.183
1612   8     45782     Wait:UserReq  0:00:00.655   0:00:00.187    7:49:39.183
1616   8    109049     Wait:UserReq  0:00:00.062   0:00:00.015    7:49:39.183
1704   8     18566     Wait:UserReq  0:00:00.015   0:00:00.000    7:49:39.168
1708   8     12453     Wait:UserReq  0:00:00.031   0:00:00.015    7:49:39.168
 156  11       520       Wait:Queue  0:00:00.000   0:00:00.000    7:49:38.013
2264   8     14156     Wait:UserReq  0:00:00.000   0:00:00.000    7:49:23.412
2340   8     27361     Wait:UserReq  0:00:00.780   0:00:00.015    7:49:14.925
2344   8     16580     Wait:UserReq  0:00:00.015   0:00:00.000    7:49:13.350
2352   9     13742     Wait:UserReq  0:00:00.015   0:00:00.000    7:49:13.334
3692   8     34862     Wait:UserReq  0:00:00.015   0:00:00.000    7:44:19.370
6660   8       354       Wait:Queue  0:00:00.000   0:00:00.000    6:10:44.062
5628   8       134     Wait:UserReq  0:00:00.015   0:00:00.000    0:02:58.583
6020   8        92     Wait:UserReq  0:00:00.015   0:00:00.000    0:00:20.698
4828   8        86     Wait:UserReq  0:00:00.000   0:00:00.000    0:00:20.698

pslist

-d显示线程明显；

-m 显示内存明显；

-t 显示进程树；

-x 显示进程、内存、线程明细；

name 显示指定进程的信息；

-e 精确匹配指定的进程名称；